Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area. However, as devices are decreased in size, manufacturing and reliability issues arise. For example, as the structure size in electronics such as integrated circuits (ICs) is decreased, the problem of electromigration increases.
Electromigration is a transport of material caused by the gradual movement or migration of atoms in a conductor resulting from current flow, due to momentum transfer between conducting electrons and diffusing metal atoms. The electromigration effect can be significant in applications in which high current densities and high temperatures are used, such as in microelectronics. Electromigration decreases reliability of integrated circuits, and can lead to the eventual loss of one or more connections or intermittent failures. The migration of atoms can cause thinning or voids at one end of a conductive line due to vacated atoms, and can cause hillocks or a build-up of material at the other end of the conductive line due to accumulated atoms. The changes in the shape of the conductive line can cause increased resistance and can result in open circuits or short circuits.
What are needed in the art are improved methods and structures for testing and characterizing electromigration in conductive material layers of semiconductor devices.
An electrically programmed fuse (eFuse) is an on-chip component of semiconductor devices that is programmed using electromigration, by running a high amount of current through the eFuse. EFuses are used to alter ICs by connecting or disconnecting redundant circuits or memory cells, to repair the ICs or increase the number of usable ICs on a wafer, for example.
What are also needed in the art are improved eFuse structures and methods of manufacture thereof.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.